The invention is based on a fuel injection pump as generally described hereinafter. In a known fuel injection pump of this kind, equipped with an equal-pressure relief valve, a filler piece containing the relief valve is used, instead of a filler piece otherwise required for reducing the clearance volume and held by the pressure valve spring inside the tube fitting piece, and it may also serve if necessary as a stroke limitation means for the pressure valve body. This structural type requires little space, and pressure valves, whether or not equipped with a return-feed shoulder, can be modified and converted into equal-pressure relief valves while retaining the most important structural components of the generally available size. Conventional fuel injection pumps now available on the market can thus be modified or retrofitted easily. However, attempts to use such valves have heretofore failed, among other reasons because during the installation or removal of the valve or valve body, the valve spring of the relief valve tended to cause the component unit to fly apart. This meant that individual structural components might be lost, or might even fall into the pump work chamber without being observed, causing the destruction of the entire injection pump with the attendant errors as a consequence.